As a light emitting element using an electroluminescence (EL) phenomenon, an electroluminescence (hereinafter, referred to also as “EL”) element is known. An EL element is capable of emitting light of any of various colors, namely, light of any of various wavelengths by selecting a light emitting material to be contained in a light emitting layer. Such an EL element is now progressively applied to display devices and illumination devices. Especially, an organic EL element using an organic material as the light emitting material is now a target of attention.
An organic EL display device including an organic EL element for display includes a substrate and pixels located in a matrix on the substrate, and each of the pixels includes an organic EL element as a light emitting element and a switching element controlling the light emission of the light emitting element. The organic EL display device controls the switching device of each pixel to be on or off to display any image on the entirety of a display region.
In a common organic EL display device, pixel electrodes are each enclosed by an insulating material such as a resin or the like provided along a periphery of the pixel electrode. Thus, each of the pixel electrodes is demarcated, and a light emitting element is formed in the enclosed area (Japanese Laid-Open Patent Publication No. 2012-160388).
Such an enclosing portion formed of an insulating material is generally referred to as a bank. A bank flattens the roughness caused by contact holes formed to connect the pixel electrodes and the switching elements to each other or prevents shortcircuiting from occurring between the pixel electrodes included in EL elements and a common electrode. In the case where the light emitting layer is formed by a printing method, the bank acts as a wall demarcating the printing area.